NEW YORK (Reuters Health) - If you thought that smoking tobacco through a waterpipe was safer than cigarettes, think again: Compared to cigarette smoking, a waterpipe -- also called a hookah or shisha -- delivers more deadly carbon monoxide and roughly the same amount of addictive nicotine, according to a new study.

"This study can be used to dispel the myth that waterpipe tobacco smoking is a less lethal way of smoking tobacco," co-author Dr. Thomas Eissenberg of the Virginia Commonwealth University in Richmond wrote in an email to Reuters Health.

"The take home message is clear," Eissenberg added. "If people are smoking tobacco in a waterpipe to avoid poisonous gasses like carbon monoxide and addictive chemicals like nicotine, they are making a big mistake."

Smoking tobacco with a waterpipe has grown in popularity in the United States, especially among the 18- to 24-year-old crowd, who may think that it's less harmful than smoking cigarettes. Some estimate that as many as one in five U.S. college students use a waterpipe to smoke tobacco.

But according to Eissenberg, until now, no study has directly compared the toxic chemical exposure associated with waterpipe and cigarette smoking under controlled conditions.

Eissenberg and colleague Alan Shihadeh of the American University of Beirut in Lebanon had 31 adult volunteers complete two 45-minute smoking sessions -- one in which they smoked tobacco using a waterpipe and the other in which they smoked a single cigarette. The researchers measured blood levels of nicotine and carbon monoxide, as well as heart rate, number of puffs taken and the "puff volume."

The results, Eissenberg noted in a prepared statement, "provide concrete, scientific evidence that contradicts the oft-repeated myth that waterpipe tobacco smoking does not involve users inhaling the same harmful chemicals that cigarette smokers do."

"In fact, comparing a waterpipe use episode to a single cigarette, waterpipe smokers in our study were exposed to three times the carbon monoxide," he told Reuters Health.

"This exposure is a major health risk because, in cigarette smokers, long-term carbon monoxide exposure is thought to be responsible for the deaths of over 100,000 Americans each year" from heart disease, Eissenberg noted.

In addition, the researchers found that peak nicotine levels did not differ in the waterpipe and cigarette smokers "Without doubt," Eissenberg said, a single waterpipe use exposes users to at least as much nicotine as a single cigarette, if not more.

There was also evidence that relative to a cigarette, waterpipe tobacco smoking generates more than 40 times the smoke volume. Both cigarette and waterpipe smoking increased heart rate.

"Too many waterpipe smokers tell me that they know that cigarettes will kill them, but believe waterpipe tobacco smoking will not," Eissenberg noted. "The results of this study...suggest that waterpipe tobacco smokers and cigarette smokers almost certainly face many of the same health risks."

The study, appearing in the American Journal of Preventive Medicine, was supported by grants from the U.S. Public Health Service.